08-03-2020 Council work Session Packet

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Addressed in Stormwater Management Plan. Applicant shall update the SWPPP. SWPPP updated per the SWMP. 15.The applicant shall verify the lot lines on Lot 12 Block 4, Lot 4 Block 1, and Lot 5 Block 1. It appears the structures may encroach on the drainage and utilit y easements. Plan updated. The applicant shall verify the lot lines on Lot 24 Block 7. It appears the structure may encroach on the drainage and utility easement. Lot lines revised in this area as well as pad locations. 16.The applicant shall include the bottom elevation of the infiltration basin on the grading plans. Elevations added. Applicant shall verify the bottom elevation, as it differs between HydroCAD model, plans, and Appendix C. Verify the culvert outlet elevation; outlet should be above the exfiltration elevation. As a note: planting medium is not necessary below the bottom of the infiltration basin. The infiltration is not intended to provide above-ground retention to prevent oversaturating the back yards of the adjacent lots. The area is a flat infiltration swale area. The plan and HydroCAD Model now show the outlet elevation equal to the infiltration basin bottom. Note that with this design, infiltration volume credit cannot be claimed for IB10 and the SWMP must be updated. Volume of infiltration is the ponded volume (volume from basin bottom to the outlet elevation). Outlet for infiltration basin 10 raised 0.5’ above bottom of basin. Per RCWD comments, infiltration volumes have been updated. 17.The applicant shall verify the retention volume calculation for Pond 400 in Appendix C as there appears to be an error. The volumes are correct. 18.If needed, the opportunity may exist to maximize infiltra tion at the infiltration basin b y constructing the basin to minimize the separation between the bottom of the basin and the water table. The basin needs minimum 3 feet separation from the water table and cannot be lowered. 19.The applicant shall verify that the HWL of the Infiltration Basin is 2.0 feet below the low entry elevations of surrounding buildings. Separation requirement is met 20.The applicant shall display and label emergenc y overflows with spot elevat ions and drainage arrows at all ponds and sags, specificall y at the intersection of Street A and Street C and at the cul-de-sac of Street C. EOF’s added. 21. The applicant shall confirm that there is a 10-ft. setback between the HW L of the infiltration basin and the drainage and utility easements. HW L is covered by easement. 22. The applicant shall verify that the top berm of stormwater ponds is 2 ft. above the HW L of the pond. Berm updated. 23.The applicant shall label the safety bench on the plans. It shall be at least 10-ft wide. The pond slope cannot be greater than a 3:1 slope. Comment noted. The applicant shall label the safety bench on the plans. Safety bench label added. 24. The storm sewer system and grading in the rear yards of Lot 1-3 Block 1 should be